/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.socket.adapter.jetty;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.URI;
import java.security.Principal;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;

import org.eclipse.jetty.websocket.api.RemoteEndpoint;
import org.eclipse.jetty.websocket.api.Session;
import org.eclipse.jetty.websocket.api.WebSocketException;
import org.eclipse.jetty.websocket.api.extensions.ExtensionConfig;

import org.springframework.http.HttpHeaders;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.CollectionUtils;
import org.springframework.web.socket.BinaryMessage;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.PingMessage;
import org.springframework.web.socket.PongMessage;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketExtension;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.adapter.AbstractWebSocketSession;

/**
 * A {@link WebSocketSession} for use with the Jetty 9.4 WebSocket API.
 *
 * @author Phillip Webb
 * @author Rossen Stoyanchev
 * @author Brian Clozel
 * @author Juergen Hoeller
 * @since 4.0
 */
public class JettyWebSocketSession extends AbstractWebSocketSession<Session> {

    private final String id;

    @Nullable
    private URI uri;

    @Nullable
    private HttpHeaders headers;

    @Nullable
    private String acceptedProtocol;

    @Nullable
    private List<WebSocketExtension> extensions;

    @Nullable
    private Principal user;


    /**
     * Create a new {@link JettyWebSocketSession} instance.
     *
     * @param attributes attributes from the HTTP handshake to associate with the WebSocket session
     */
    public JettyWebSocketSession(Map<String, Object> attributes) {
        this(attributes, null);
    }

    /**
     * Create a new {@link JettyWebSocketSession} instance associated with the given user.
     *
     * @param attributes attributes from the HTTP handshake to associate with the WebSocket
     *                   session; the provided attributes are copied, the original map is not used.
     * @param user       the user associated with the session; if {@code null} we'll fallback on the
     *                   user available via {@link org.eclipse.jetty.websocket.api.Session#getUpgradeRequest()}
     */
    public JettyWebSocketSession(Map<String, Object> attributes, @Nullable Principal user) {
        super(attributes);
        this.id = idGenerator.generateId().toString();
        this.user = user;
    }


    @Override
    public String getId() {
        return this.id;
    }

    @Override
    @Nullable
    public URI getUri() {
        checkNativeSessionInitialized();
        return this.uri;
    }

    @Override
    public HttpHeaders getHandshakeHeaders() {
        Assert.state(this.headers != null, "WebSocket session is not yet initialized");
        return this.headers;
    }

    @Override
    public String getAcceptedProtocol() {
        checkNativeSessionInitialized();
        return this.acceptedProtocol;
    }

    @Override
    public List<WebSocketExtension> getExtensions() {
        Assert.state(this.extensions != null, "WebSocket session is not yet initialized");
        return this.extensions;
    }

    @Override
    public Principal getPrincipal() {
        return this.user;
    }

    @Override
    public InetSocketAddress getLocalAddress() {
        checkNativeSessionInitialized();
        return getNativeSession().getLocalAddress();
    }

    @Override
    public InetSocketAddress getRemoteAddress() {
        checkNativeSessionInitialized();
        return getNativeSession().getRemoteAddress();
    }

    @Override
    public int getTextMessageSizeLimit() {
        checkNativeSessionInitialized();
        return getNativeSession().getPolicy().getMaxTextMessageSize();
    }

    @Override
    public void setTextMessageSizeLimit(int messageSizeLimit) {
        checkNativeSessionInitialized();
        getNativeSession().getPolicy().setMaxTextMessageSize(messageSizeLimit);
    }

    @Override
    public int getBinaryMessageSizeLimit() {
        checkNativeSessionInitialized();
        return getNativeSession().getPolicy().getMaxBinaryMessageSize();
    }

    @Override
    public void setBinaryMessageSizeLimit(int messageSizeLimit) {
        checkNativeSessionInitialized();
        getNativeSession().getPolicy().setMaxBinaryMessageSize(messageSizeLimit);
    }

    @Override
    public boolean isOpen() {
        return getNativeSession().isOpen();
    }


    @Override
    public void initializeNativeSession(Session session) {
        super.initializeNativeSession(session);

        this.uri = session.getUpgradeRequest().getRequestURI();

        HttpHeaders headers = new HttpHeaders();
        headers.putAll(session.getUpgradeRequest().getHeaders());
        this.headers = HttpHeaders.readOnlyHttpHeaders(headers);

        this.acceptedProtocol = session.getUpgradeResponse().getAcceptedSubProtocol();

        List<ExtensionConfig> jettyExtensions = session.getUpgradeResponse().getExtensions();
        if (!CollectionUtils.isEmpty(jettyExtensions)) {
            List<WebSocketExtension> extensions = new ArrayList<>(jettyExtensions.size());
            for (ExtensionConfig jettyExtension : jettyExtensions) {
                extensions.add(new WebSocketExtension(jettyExtension.getName(), jettyExtension.getParameters()));
            }
            this.extensions = Collections.unmodifiableList(extensions);
        }
        else {
            this.extensions = Collections.emptyList();
        }

        if (this.user == null) {
            this.user = session.getUpgradeRequest().getUserPrincipal();
        }
    }


    @Override
    protected void sendTextMessage(TextMessage message) throws IOException {
        getRemoteEndpoint().sendString(message.getPayload());
    }

    @Override
    protected void sendBinaryMessage(BinaryMessage message) throws IOException {
        getRemoteEndpoint().sendBytes(message.getPayload());
    }

    @Override
    protected void sendPingMessage(PingMessage message) throws IOException {
        getRemoteEndpoint().sendPing(message.getPayload());
    }

    @Override
    protected void sendPongMessage(PongMessage message) throws IOException {
        getRemoteEndpoint().sendPong(message.getPayload());
    }

    private RemoteEndpoint getRemoteEndpoint() throws IOException {
        try {
            return getNativeSession().getRemote();
        }
        catch (WebSocketException ex) {
            throw new IOException("Unable to obtain RemoteEndpoint in session " + getId(), ex);
        }
    }

    @Override
    protected void closeInternal(CloseStatus status) throws IOException {
        getNativeSession().close(status.getCode(), status.getReason());
    }

}
